The era eventually deemed OBD-I was a difficult one for consumers and independent mechanics alike. Between about 1981 and 1995, manufacturers created their own proprietary vehicle data connections, diagnostic tools, code parameters, DTC numbering, and display methodologies. It created a tangled web that was a relative nightmare for anyone without access to an OEM diagnostic computer. Paper clips in hand, Americans dealt with the system until standardization was forced upon the industry by California's Clean Air Resources Board (CARB). OBD-II was mandated for 1996 model year vehicles and introduced a whole new problem for the independent and shade tree mechanics and aftermarket parts manufacturers.
All manufacturers selling vehicles in the United States were united in their diagnostics and coding for the first time in 1996. Providing the diagnostic equipment to their franchised dealers, they ensured their service departments could diagnose and repair all vehicles from 1996 onward. However, they were keen to keep their diagnostics to themselves, and saw no reason to publish or share such information.
It took just eight months before a lawsuit was filed. Nine aftermarket parts associations filed suit against the U.S. federal Environmental Protection Agency (EPA), California's EPA, and CARB itself. The allegation: Withholding OBD-II codes and diagnostic tools meant manufacturers' dealers had an unfair monopoly. This was thus in violation of the Clean Air Act, 1963 legislation that experienced major overhauls in 1970 and 1990.
The plaintiffs said both the EPA and California regulators in their application of OBD-II rules prevented independent providers from equal competition to diagnose and repair new vehicles, as well as the manufacture of replacement parts (for which complete OBD-II information was necessary). The case was heard in August, in the district court of Washington, D.C. Background tension was felt at the automakers, who did not want to be forced to open OBD-II to the broader market.
The court ruled against the aftermarket associations and their claims. The law at issue was the "deemed to comply" rule, where the EPA said if a car met stringent California OBD-II rules that it also satisfied the federal Clean Air Act. The court said the Clean Air Act gave the EPA the discretion to coordinate federal standards, and it did not unlawfully restrict aftermarket competition.
Automakers saw the case as a huge win, and went about conducting their OBD-II business. However, the case created greater visibility into what became known as the right to repair movement. The EPA directly addressed the original issue raised by the aftermarket companies in 2003, when it passed the Service Information Rule.
Effective from Aug. 26, 2003, the rule stated auto manufacturers must provide full emissions related repair and service information in full text via public websites (a list is here). It also required OEMs to provide outside companies with the data necessary to produce automotive diagnostic and programming tools. Further it required the OEM-specific diagnostic devices to be made available for purchase by any interested party. Since that time, the right to repair debate has only intensified as vehicles became continually more complex.
Other countries took notice of OBD-II, and would add very similar regulations thereafter. The European Union acted in 2004 to make its version, EOBD, mandatory on all vehicles sold in the EU. Australia and New Zealand followed OBD-II directly, beginning on Jan. 1, 2006. That same year, the US applied OBD-II standards to heavier vehicles, as it was required for all GWVRs under 14,000 pounds.
In 2007, California increased its standard for all vehicles over 14,000 pounds, and declared they must support EMD (Engine Manufacturer Diagnostics) or OBD-II. The following year a tech upgrade was required in all vehicles sold in the United States, to ISO 15765-4. An international standard, it mandated identifier lengths (11-bit, 29-bit) and bus speeds of either 250 kbps or 500 kbps.
The most recent implementation of a new OBD-II rule occurred in 2010, when the United States mandated it for vehicles with a GWVR of over 14,000 pounds. There was a four-year phase in period for large vehicles, more generous than passenger cars years prior. All large vehicles were required to be in compliance by the 2013 model year.
Throughout the 2000s, aftermarket diagnostic technology advanced and became more useful. This led to the broad availability of affordable aftermarket diagnostic connectors. These initially consisted of lower-cost handheld units that plugged directly into the OBD-II port of a vehicle to read codes.
Subsequently, USB-based units plugged into a laptop and worked with various types of software (often manufacturer group specific) to provide real-time diagnostics, codes, and programming capabilities to consumers and independent mechanics. The ultimate iteration of the OBD-II reader includes all of the above features, and is now wireless. Using a Bluetooth-capable plug in a vehicle's port, it will interface in real-time with various diagnostic apps installed on a smartphone. It's easier than ever for a consumer to see detailed information on the inner workings of their automobile, and even to perform coding and turn on features that might be "off" from the factory due to regional settings or corporate greed.
Unfortunately (and this may be news), OBD-II is at the end of its lifespan. Beginning in 2025 select vehicles began to phase in the next generation of diagnostics. Called Unified Diagnostic Services or UDS, it's nearly upon us.
UDS becomes a requirement for US-bound vehicles in the 2027 model year. But maybe it's not a bad thing we're entering a brave new world of diagnostics. In our next installment we'll take a look at exactly what UDS means, and how it will change the entire basis of car diagnostics in the very near future.
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